The incorporation of particulate inorganic solids into polymer matrices has been performed for many years, and, over the years, particulate inorganic solids have been and continue to be incorporated into polymer matrices for many reasons. For example, they may be used as fillers. They may also be used to impart better physical and chemical attributes to polymer matrices, including decreased chemical activity and improved thermal stability, especially lacing resistance in extruded polymer film applications. In order to obtain different benefits, particulate inorganic solids may be treated in different ways, including by adding surface treatments.
Commonly used particulate inorganic solids for incorporation into polymer matrices include titanium dioxide and kaolin. Known surface treatments that have been applied to these solids include silanes, alkanolamines, polyols, organophosphoric acids, organosulfonic acids, and phosphorylated polyenes. The optimal treatment will in part depend on the attributes that one wants in a treated solid, which will in part depend on the application in which it will be used. Often one wants to provide a hydrophobic particulate solid that is stable, easy to prepare, cost effective, able to be dispersed to a high degree in polymers, and not reactive in the presence of other additives such as lithopone. However, despite the numerous known surface treatments, for various reasons, including cost and desired properties, no known surface treatments are ideal for all applications. Thus, there is always a need to develop new and better treatments for particulate solids.
Surprisingly, it was found that by treating an inorganic particulate solid with an organophosphinic compound, a composition that has good dispersiblity in polymer matrices could be produced. The present invention is directed to these treated inorganic particulate solids, methods for making them, and uses for them.